Normally closed fire doors are usually closed under the action of door closers, so they can prevent fire and smoke from spreading in case of fire. Normally open fire doors are usually opened under the action of fire door releaser. In case of fire, the fire door releaser automatically releases, and the fire door is closed under the action of door closer and releaser, thus preventing fire and smoke from spreading.

ZHTdoors menyako ea mollo, lilemo tse 31 tsa boiphihlelo ba tlhahiso menyakong ea mollo le Windows. Menyako e ka sehloohong ea mollo oa UL, mamati a mollo oa EN, mamati a mollo a BS EN, joalo-joalo,.Re na le setifikeiti.ZHTdoors tšehetso OEM le mahala moralo.Melemo ea rona: boleng bo botle, theko ea fektheri, tšebeletso e ntle.Rea u amohela ho buisana le rona.